Disposable hypodermic syringes, one of the most widely used medical devices in existence, are also one of the most dangerous to deal with as medical waste. For obvious reasons their use and disposal are subject to regulation at all levels of government. After professional use they are deemed Regulated Medical Waste and the cost for their disposal by licensed handlers under burdens of manifests and regulations which touch every step of the way from the patients they penetrate to the end at either licensed incinerators or special refuse centers. Despite the burdensome efforts of control and the consequent expense to society, there are recurring leaks in the system hazardous to the health of many.
Technology for rendering disposable syringes discernably harmless in a practical, cost-effective way at their point of use has been sought since the time of their acceptance by the medical industry. The first attempts involved simply melting down the thermoplastic parts of the syringes as shown in U.S. Pat. No. 3,958,936, May 25, 1976. Randomly exposed needles, lack of sterility, and lack of means to verify sterility, even if achieved, rendered the waste dangerous and the procedure was abandoned. The art of melting down needles was advanced by Swedish Patent No. 8003576-9, published April 1981, which addressed the problem of randomly exposed needles in the plastic waste by providing supplemental plastic which melted at or below the syringe melting temperature. Sterility and its verifiability remained, however, as a bar to acceptance and use.
Color-changing flags in the form of inks, paints and films which change color when exposed to desired temperatures are used in connection with sterilization and other thermal procedures. They are widely used as an aid to medical professionals to monitor their autoclaves and dry heat sterilizers. If the color has not changed when the heating cycle ends, an otherwise presentable looking scalpel, for example, is not used and recalibration of the sterilizer must be ordered. It is a useful tool for such purposes but it cannot speak beyond its own surfaces. It cannot verify that the heat it felt reached the needle, nor can it deal with time functions. A waste manager bent on mischief for example can easily spot-radiate the patch and proclaim his processed batch sterile at substantial savings of time and energy. It does little good, therefore, for reputable manufacturers to place the most reliable color-changing patch available on medical instruments such as syringes in an attempt to prove the heated or melted down syringes are sterile.
A recent advance in the technology is disclosed in the Applicant's U.S. Pat. Nos. 4,992,217 and 5,078,924 in which verifiable on-site sterilization as waste of various medical items including disposable syringes is achieved by the use of special temperature-calibrated thermoplastic formulated, shaped and arranged to achieve liquefaction or phase change only at a temperature and within a time frame which equals or exceeds the scientifically established and accepted temperature-time death curve for the destruction of all known microbial life, including spore forms, which infect human and other animal life. Sufficient plastic is provided in configurations which insure that molten plastic reaches and covers the needles. The intended purpose of this product cannot be frustrated by either intentional or unintentional error on the part of the processor. Furthermore, if a manufacturer were to be unreliable in the first place, condemning evidence would survive the treatment process.
The present invention represents a further advance in the technology of on-site processing and sterilization of disposable thermoplastic syringes per se by achieving further overall cost reduction, improved verification and simplification of the processing procedure, using the basic technology of U.S. Pat. Nos. 4,992,217 and 5,078,924.